Cathode collector plate and cylindrical lithium ion battery

Abstract

The invention provides a cathode current collector plate and a cylindrical lithium ion battery, the cathode current collector plate comprises a plate body and a flange, the plate body is in the shape of a closed pattern formed by alternately connecting a plurality of arc edges and a plurality of concave edges end to end in sequence, the flange is arranged on the arc edges, the concave edges are limited at the outer periphery of the plate body to form a gap, and the flange is arranged on the outer periphery of the plate body. The disc body is provided with a center hole located in the center of the disc body and auxiliary holes located in the periphery of the center hole, the area of the disc body is S1 when the disc body is not provided with the center hole, the auxiliary holes and the notches, the area of the notches formed by taking the edge line of the outer periphery of the disc body as the reference is S2, and the range of S2 / S1 is 2%-10%. By arranging the notches on the outer periphery of the disc body and reasonably setting the sizes of the notches, on one hand, the exhaust efficiency can be improved so as to improve the safety of the battery, and on the other hand, the electrolyte injection efficiency can be improved, the electrolyte injection time can be shortened, the production efficiency can be improved, and the manufacturing cost of the battery can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a negative electrode current collector and a cylindrical lithium-ion battery. Background Art

[0002] At present, in 46 series cylindrical lithium-ion batteries, the negative electrode current collector usually includes a disc body and a circle of flanges located at the periphery of the disc body. When assembling the cylindrical lithium-ion battery, the disc body is welded to the negative end of the winding core, and the outer surface of the flange is attached to the inner surface of the shell and connected by penetration welding, so that the shell and the negative electrode of the winding core are conductively connected. In addition, some 46 series cylindrical lithium-ion batteries will adopt a liquid injection scheme of injecting electrolyte on the negative electrode side, and a pressure relief scheme of setting an explosion-proof protection device on the negative electrode cover. However, for cylindrical lithium-ion batteries using the above-mentioned injection scheme, the flange of the aforementioned negative electrode current collecting disk is tightly connected to the inner wall of the shell, and the electrolyte can only enter the battery through the injection hole in the middle of the negative electrode current collecting disk. The injection efficiency is low and overflow problems are very likely to occur. For cylindrical lithium-ion batteries using the above-mentioned pressure relief scheme, if a short circuit or other thermal runaway occurs during use, a large amount of gas will be generated in the shell, and the disk body and the flange will prevent the gas from being discharged from the negative electrode side, thereby increasing the safety risk of the battery.

[0003] In addition, for the flange of the above structure, when the negative electrode current collector is welded to the shell, the weld line formed is longer, and the longer the weld, the higher the risk of welding quality problems. For example, leakage, cold welding, missing welding and other welding quality problems may occur at the weld line, thereby increasing the internal resistance of the battery cell. Summary of the invention

[0004] The embodiments of the present application provide a negative electrode current collecting plate and a cylindrical lithium-ion battery to at least solve the technical problems of low liquid injection efficiency, low exhaust rate and high battery internal resistance of existing cylindrical lithium-ion batteries.

[0005] A first aspect of the present application provides a negative electrode current collector disk for a cylindrical lithium-ion battery, comprising a disk body and a flange protruding along one side of the outer peripheral edge of the disk body, wherein the shape of the disk body is a closed figure composed of a plurality of arc edges and a plurality of concave edges alternately connected end to end in sequence, the flange is arranged on the arc edge, and the concave edge defines a notch at the outer peripheral edge of the disk body, the disk body is provided with a center hole located at its center and at least one auxiliary hole located on the periphery of the center hole, the area of ​​the disk body is S1, and the total area of ​​the notch formed with the outer peripheral edge line of the disk body as a reference is S2, and the range of S2 / S1 is between 2% and 10%, wherein the area of ​​the disk body is the area of ​​the disk body when the center hole, the auxiliary hole and the notch are not provided.

[0006] The negative electrode current collector according to the embodiment of the present application has at least the following beneficial effects:

[0007] Firstly, by providing a notch on the outer periphery of the disk and by reasonably setting the size of the notch, on the one hand, when a short circuit or thermal runaway occurs inside the battery and a large amount of gas is produced, part of the gas can be diverted through the notch, thereby improving the exhaust efficiency and improving the safety of the battery; on the other hand, during the injection process, when the electrolyte flows into the disk surface of the disk, part of the electrolyte will flow directly into the battery through the central hole and the auxiliary hole, while part of the electrolyte will reach the outer periphery of the disk along the disk surface. Due to the presence of the notch, this part of the electrolyte will flow into the battery along the notch, thereby improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing the manufacturing cost of the battery.

[0008] Secondly, since the flange is not a complete circular ring structure, the length of the welding line between it and the shell can be effectively reduced, thereby reducing the risk of leakage, cold welding and welding leakage at the welding point, and further reducing the internal resistance of the battery.

[0009] Furthermore, since the flange is only provided at the edge of the arc, the weight of the negative electrode collector can be reduced to a certain extent, thereby improving the energy density of the battery.

[0010] In a possible implementation manner, the area of ​​the central hole is S3, and the range of S3 / S1 is 1% to 3%.

[0011] By reasonably setting the range of S3 / S1, it is possible to take into account the injection efficiency and exhaust efficiency of the negative electrode collector disc while ensuring a good welding effect between the disc body and the winding core, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0012] In a possible implementation manner, the total area of ​​the auxiliary holes is S4, and the ratio S4 / S1 is in the range of 9% to 21%.

[0013] By reasonably setting the range of S4 / S1, it is possible to take into account the injection efficiency and exhaust efficiency of the negative electrode collector disc while ensuring a good welding effect between the disc body and the winding core, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0014] In a possible implementation manner, the circumference of the disk body is H1, the total arc length of the flange is H2, and the range of H2 / H1 is 42% to 58%.

[0015] By reasonably setting the range of H2 / H1, it is possible to ensure a good welding effect between the flange and the shell while ensuring that the negative electrode collector is lighter, thereby improving the energy density of the battery and effectively avoiding increasing the internal resistance of the battery.

[0016] In a possible implementation manner, the circumference of the disk body is H1, the total arc length of the notch is H3, and the range of H3 / H1 is 25% to 38%.

[0017] By reasonably setting the range of H3 / H1, it is possible to take into account the injection efficiency and exhaust efficiency of the negative electrode collector disc while ensuring a good welding effect between the disc body and the winding core, and it can also effectively avoid increasing the internal resistance of the battery.

[0018] In a possible implementation manner, the shape of the concave edge is arc-shaped, and the maximum depth of the notch is H4, and the range of H4 is 2 to 5 mm.

[0019] By reasonably setting the range of the maximum depth H4 of the notch, it is possible to take into account the injection efficiency and exhaust efficiency of the negative electrode collector disc while ensuring a good welding effect between the disc body and the winding core, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0020] In a possible implementation manner, the radius of the disk body is L1, the distance between the inner edge of the auxiliary hole and the center of the central hole is L2, and the range of L2 / L1 is 18% to 36%.

[0021] By reasonably setting the range of L2 / L1, it is possible to take into account the structural strength of the connection part between the central hole and the auxiliary hole while ensuring the auxiliary injection effect of the auxiliary hole.

[0022] In a possible implementation manner, the auxiliary hole is a waist-shaped hole, and the long axis direction of the auxiliary hole is consistent with the radius direction of the disk body.

[0023] By reasonably designing the shape and arrangement of the auxiliary holes, the opening area of ​​the auxiliary holes can be effectively increased without affecting the welding area, thereby improving the effect of auxiliary liquid injection.

[0024] In a possible embodiment, the number of the arc edges, the concave edges and the auxiliary holes is 4, the 4 arc edges and the 4 auxiliary holes are arranged in one-to-one correspondence, and the midpoints of the corresponding arc edges, the centers of the auxiliary holes and the center of the center hole are collinear.

[0025] By reasonably setting the number and arrangement of arc edges, concave edges and auxiliary holes, the exhaust efficiency and injection efficiency can be balanced and improved while the structural strength of the disc body can be effectively guaranteed, and the weldable area between the disc body and the winding core can be guaranteed.

[0026] The second aspect embodiment of the present application provides a cylindrical lithium-ion battery, comprising a shell, a winding core and the negative electrode collector disk provided by the first aspect embodiment above, the disk body of the negative electrode collector disk is connected to the negative end of the winding core, and the flange of the negative electrode collector disk is connected to the shell wall of the shell by laser penetration welding.

[0027] The cylindrical lithium-ion battery according to the embodiment of the present application has at least the following beneficial effects:

[0028] In the cylindrical lithium-ion battery of the embodiment of the present application, a notch is provided on the outer peripheral edge of the negative electrode current collector, which helps to improve the internal exhaust rate and injection efficiency of the battery, thereby improving the safety of the battery and reducing the manufacturing cost of the battery. In addition, the flange of the negative electrode current collector is only provided at the edge of the arc, thereby improving the energy density and reducing the internal resistance of the battery, thereby improving the performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0030] Figure 1 is a cross-sectional schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of the present application;

[0032] Figure 3 yes Figure 2 Schematic diagram of the assembly of the middle negative electrode current collector, winding core and shell;

[0033] Figure 4 yes Figure 2 A schematic front view of the middle negative electrode current collecting plate;

[0034] Figure 5 yes Figure 2 A schematic diagram of the area S1 of the middle negative electrode current collector;

[0035] Figure 6 yes Figure 2 A schematic diagram of the area S2 of the middle negative electrode current collector;

[0036] Figure 7 yes Figure 2 A schematic diagram of the area S3 of the middle negative electrode current collecting disk;

[0037] Figure 8 yes Figure 2A schematic diagram of the area S4 of the middle negative electrode current collecting disk;

[0038] Fig. 9 yes Figure 2 Schematic diagram of the front view of the negative electrode collector plate.

[0039] Reference numerals:

[0040] 100-negative electrode current collecting plate, 110-plate body, 111-center hole, 112-auxiliary hole, 113-notch, 114-arc edge, 115-concave edge, 120-flange;

[0041] 200-winding core, 210-positive terminal, 220-negative terminal, 230-winding core hole;

[0042] 300-housing;

[0043] 400-positive electrode cover plate assembly, 410-electrode column;

[0044] 500-negative electrode cover, 510-sealing nail. DETAILED DESCRIPTION

[0045] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0046] In the description of the present embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present embodiment.

[0047] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0048] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0049] Figure 1 is a schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application, Figure 1 In the figure, the negative electrode side of the cylindrical lithium-ion battery is on the top and the positive electrode side is on the bottom. Figure 1 As shown, the cylindrical lithium-ion battery includes a shell negative electrode current collector 100, a winding core 200, a shell 300, a positive electrode cover plate assembly 400, and a negative electrode cover plate 500. Among them, the positive terminal 210 of the winding core 200 is connected to the positive electrode cover plate assembly 400, and the positive electrode cover plate assembly 400 is provided with a pole 410 as the positive electrode of the cylindrical lithium-ion battery on the outside. The negative terminal 220 of the winding core 200 is connected to the shell 300 through the negative electrode current collector 100, and the shell 300 serves as the negative electrode of the cylindrical lithium-ion battery and is used to be electrically connected to an external electrical device.

[0050] It is understandable that the negative electrode cover plate 500 of the cylindrical lithium-ion battery is provided with an injection hole sealed by a sealing nail 510, through which electrolyte can be injected into the interior of the cylindrical lithium-ion battery through one side of the negative electrode cover plate. At the same time, a structure such as an injection explosion-proof groove can be constructed on the negative electrode cover plate 500 to open in time to release pressure when an abnormal pressure rise occurs inside the cylindrical lithium-ion battery. It is understandable that since the negative electrode collector plate 100 is arranged on the inner side of the negative electrode cover plate 500, the structure of the negative electrode collector plate 100 has a great influence on the injection and pressure release on the negative electrode side. The negative electrode collector plate 100 of the embodiment of the present application is described in detail below.

[0051] Figure 2 is a schematic structural diagram of a negative electrode current collecting disk 100 provided in an embodiment of the present application, Figure 3 yes Figure 2 A schematic diagram of the combined structure of the middle negative electrode current collecting disc 100, the winding core and the shell is shown in FIG. Figure 2 Figure 3 As shown, the negative electrode current collecting disc 100 includes a disc body 110 and a flange 120 protruding along one side of the outer periphery of the disc body 110, wherein the disc body 110 is used to connect with the negative terminal 220 of the winding core 200, and the flange 120 is used to connect with the shell 300 to form a passage between the winding core 200 and the shell 300, so that the shell 100 itself serves as the negative electrode of the cylindrical lithium-ion battery.

[0052] It is understandable that the connection between the disc body 110 and the flange 120 can be any fixed connection method. To ensure a stable connection, structural strength and processing economy, the disc body 110 and the flange 120 can be integrally connected, for example, integrally formed by stamping.

[0053] like Figure 2 and Figure 3As shown, the disc body 110 is the main structural part of the negative electrode current collector disc 100, and is in the shape of a thin sheet as a whole. A central hole 111 and a plurality of auxiliary holes 112 are provided on the disc body 110. In addition, a plurality of notches 113 are provided at the outer periphery of the disc body 110. It can be understood that the disc body 110 has two disc surfaces that are separated from each other. Figure 2 As shown, the flange 120 protrudes from the edge of the disk body 110 to one side at an angle approximately perpendicular to the disk surface, as shown in FIG. Figure 3 As shown, the disk surface on the side opposite to the protruding direction of the flange 120 can be used to weld to the negative terminal 220 of the winding core 200. In this case, the disk surface on the side where the flange 120 is located faces the opening direction of the shell 300. In the subsequent liquid injection process, the electrolyte will enter the battery through this side disk surface.

[0054] It is understandable that the cross-sectional shapes of the winding core 200 and the shell 300 of the cylindrical lithium-ion battery are both circular. Therefore, in order to facilitate the welding between the disk body 110 and the winding core 200, and to facilitate the welding between the flange 120 and the shell 300, for the negative electrode current collector 100, the outer contour of the disk body 110 is generally circular. In this embodiment, due to the presence of the notch 113, the outer contour of the disk body 110 is not a complete circular shape. Figure 4 From the perspective of the embodiment, the shape of the disk body 110 is a closed figure composed of a plurality of arc edges 114 and a plurality of concave edges 115 that are alternately connected end to end.

[0055] As mentioned above, the disk body 110 is not a complete circle, but the ends of the arc-shaped edges 114 can be extended to connect with each other to form a complete circle, so the disk body 110 can be regarded as a circular component.

[0056] like Figure 2 and Figure 3As shown, in this embodiment, the flange 120 is not a complete circular ring structure. Specifically, the flange 120 is only provided at the edge of the arc edge 114, that is, it seems that the flange 120 is divided into multiple sections by multiple notches 113. In this way, each section of the flange 120 fits well with the shell wall surface of the shell 300 and is connected by penetration welding. At the same time, by setting a notch 113 at the disconnection point of the flange 120, on the one hand, during the injection process, when the electrolyte flows into the disk surface of the disk body 110, part of the electrolyte will flow directly into the battery through the central hole 111 and the auxiliary hole 112, while part of the electrolyte will reach the outer periphery of the disk body 110 along the disk surface of the disk body 110. Due to the existence of the notch 113, this part of the electrolyte will flow into the battery along the notch 113, thereby improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing the manufacturing cost of the battery; on the other hand, when a short circuit or thermal runaway occurs inside the battery and a large amount of gas is produced, part of the gas can be diverted through the notch 113, thereby improving the exhaust efficiency and improving the safety of the battery.

[0057] It is understandable that only by providing the flange 120 at the position of the arc edge 114, the weight of the negative electrode current collector 100 can be reduced to a first degree, thereby improving the energy density of the battery. In addition, since the flange 120 is not a complete circle, the length of the welding line when it is welded to the shell 300 can be effectively reduced, thereby reducing the risk of leakage, cold welding, and leaking welding at the welding point, thereby reducing the internal resistance of the battery.

[0058] It can also be understood that, for the negative electrode current collector disk 100, the art generally adopts the method of opening pores inside the disk body 110 to improve the liquid injection efficiency, and in the design process, it is also necessary to balance the weldable area of ​​the disk body 110 itself and construct a flange 120 on the edge of the disk body 110, etc., so as to facilitate welding with the winding core 200 and the shell 300 and design welding tooling and fixtures. The present application divides the flange 120 into multiple sections and opens a notch 113 on the outer periphery of the disk body 110 to assist in liquid injection and exhaust, thereby minimizing the adverse effects on the disk body 110 and the flange 120. For example, by reasonably designing the size and shape of the notch 113, the impact on the welding of the disk body 110 can be effectively avoided.

[0059] Further, from Figure 4 From the perspective of the present invention, the notch 113 is a structure formed by being concave inward toward the center of the disk body 110 at a position where the flange 120 is not provided at the outer periphery of the disk body 110. For example, the notch 113 can be formed by removing material at the outer periphery of the disk body 110 by various methods such as mechanical cutting and laser cutting.

[0060] It is further understood that the notches 113 of various shapes may be formed on the outer periphery of the disk body 110, such as Figure 4 In this case, the notch 113 is defined by the inner concave edge 115 and the reference line of the outer periphery of the disk body 110, wherein the reference line can refer to Figures 5 to 9 The dotted line at the notch 113 in the figure is used for illustration, and the dotted line represents the shape of the disc body 110 when the notch 113 is not cut out of the disc body 110, and the dotted line is obtained by extending the outer periphery of the disc body 110 according to the direction of the original outer periphery. Of course, it is not limited to this, for example, the notch 113 can be rectangular, fan-shaped, waist-shaped, etc.

[0061] It is understandable that at least one notch 113 needs to be provided in order to facilitate auxiliary exhaust and auxiliary liquid injection at the outer periphery of the disk body 110. Of course, in order to further improve the exhaust efficiency and liquid injection efficiency, multiple notches 113 can be provided. In this case, the arc edge 114 between the multiple notches 113 also has multiple sections, and accordingly, flanges 120 can be provided on these arc edges 114 respectively. Of course, it is not limited to this. Under the premise of meeting the requirements, the number of notches 113 and flanges 120 does not need to be provided one-to-one. For example, flanges 120 may not be provided on the arc edges 114 at certain positions.

[0062] like Figure 5 As shown, in some embodiments, the number of the arc edge 114, the concave edge 115 and the auxiliary hole 112 are all 4, the 4 arc edges 114 and the 4 auxiliary holes 112 are arranged one by one, and the midpoints of the corresponding arc edges 114, the centers of the auxiliary holes 112 and the center of the central hole 111 are collinear. It can be understood that, in this way, along the radial direction of the disc body 110, the auxiliary holes 112 and the notches 113 are staggered with each other. By making the number of the arc edge 114, the concave edge 115 and the auxiliary holes 112 correspond to each other and setting them to 4, it is beneficial to balance the liquid injection and exhaust effect of the disk body 110 and the welding effect of the flange 120 and the shell 300. At the same time, the center hole 111, the auxiliary hole 112 and the arc edge 114 are set to be collinear, so as to avoid weakening the structural strength of the disk body 110 due to the collinearity of the auxiliary holes 112, the notch 113 and the center hole 111, which can effectively ensure the structural strength of the disk body 110 and ensure the area of ​​the weldable area between the disk body 110 and the winding core 200.

[0063] Furthermore, if Figure 4As shown, the auxiliary hole 112 is waist-shaped, that is, the auxiliary hole 112 is a waist-shaped hole, and its long axis direction is consistent with the radius direction of the disk body 110. It can be understood that for a large cylindrical battery, the disk surface of the negative electrode current collector disk 100 is also large. The auxiliary hole 112 is a waist-shaped hole and its long axis direction is set to extend along the radius direction of the disk body 110. Without affecting the welding area, the opening area of ​​the auxiliary hole 112 can be effectively increased, thereby improving the auxiliary liquid injection effect.

[0064] like Figure 5 and Figure 6 As shown, in some embodiments, the area of ​​the disk body 110 is S1, the total area of ​​the notch 113 is S2, and the range of S2 / S1 is 2% to 10%, that is, 2%≤S2 / S1≤10%. For example, S1 is 1604.6 mm 2 , S2 is 95.56mm 2 , S2 / S1 is 5.96%. Figure 5 As shown, the area S1 of the disk body 110 refers to the disk surface area of ​​the disk body 110, that is, the area of ​​the disk body 110 when the center hole 111, the auxiliary hole 112 and the notch 113 are not provided. Figure 6 As shown, the total area of ​​the notch 113 is S2, which is the sum of the areas of the closed figure defined by the concave edge 115 and the reference line (dashed line in the figure) of the outer periphery of the disk body 110. It can be further understood that, for a single notch 113, its area refers to the area defined by the outer periphery edge line of the disk body 110 as the reference line and the boundary line of the notch 113 itself, i.e., the concave edge 115.

[0065] It is understandable that if the total area S2 of the notch 113 is too small, on the one hand, during the injection process, the notch 113 does not significantly improve the injection efficiency, and there is also a risk of electrolyte overflow, which causes the shell 300 to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the notch 113, and the effect of improving battery safety is limited. On the contrary, if the total area S2 of the notch 113 is too large, the notch 113 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the actual effective welding area between the disk body 110 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, resulting in excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in the welding area will lead to an increase in the internal resistance of the battery. By setting the range of S2 / S1 to 2% to 10%, it is possible to ensure good welding effect between the disc body 110 and the winding core 200 while taking into account the injection efficiency and exhaust efficiency of the disc body 110, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0066] As mentioned above, in this embodiment, a central hole 111 is formed on the disk body 110. The central hole 111 is formed at the center of the disk body 110 and is used to inject electrolyte into the battery. It should be noted that the center of the disk body 110 may be the center of the disk body 110. Figure 1 It is understood that the winding core 200 is made by a winding process, and a circular winding core hole 230 is formed at the center of the winding core 200 after winding. To match the shape of the winding core hole 230, the shape of the center hole 111 is preferably circular. In this case, the center hole 111 is co-centered with the disk body 110. It is understood that the diameter of the center hole 111 can be specifically selected according to the balance between the injection efficiency and the weldable area.

[0067] Furthermore, if Figure 5 and Figure 7 As shown, in some embodiments, the area of ​​the center hole 111 is S3, and the range of S3 / S1 is 1% to 3%, that is, 1%≤S3 / S1≤3%. For example, the area of ​​the center hole 111 is 28.27mm 2 , S1 is 1604.6mm 2 , S4 / S1 is 1.76%. The center hole 111 is located at the center of the disk body 110, and the number thereof is 1. Therefore, the area S3 of the center hole 111 here only refers to the area of ​​the center hole 111 itself.

[0068] It is understandable that if the area S3 of the center hole 111 is too small, on the one hand, during the injection process, due to the narrow injection channel, the electrolyte is difficult to be injected into the battery, and the injection time increases, which will lead to a decrease in the injection efficiency; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the center hole 111, which reduces the safety of the battery. On the contrary, if the area S3 of the center hole 111 is too large, the center hole 111 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the actual effective welding area between the disk body 110 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety issues such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance value of the battery. By setting the range of S3 / S1 to 1% to 3%, it is possible to ensure good welding effect between the disc body 110 and the winding core 200 while taking into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disc 100, and also effectively avoid increasing the internal resistance of the battery.

[0069] As mentioned above, in this embodiment, the disc body 110 is provided with a through auxiliary hole 112, which is provided at the periphery of the central hole 111 to assist the injection of electrolyte. It is understood that the size of the auxiliary hole 112 can be specifically selected based on the balance between the injection efficiency and the weldable area.

[0070] Furthermore, if Figure 5 and Figure 8 As shown, in some embodiments, the total area of ​​the auxiliary holes 112 is S4, and the range of S4 / S1 is 9% to 21%, that is, 9%≤S4 / S1≤21%. For example, the total area of ​​the auxiliary holes 112 is 226.27 mm 2 , S1 is 1604.6mm 2 , S4 / S1 is 14.1%. The total area S4 of the auxiliary holes 112 refers to the sum of the areas of all the auxiliary holes 112 on the disk body 110.

[0071] It is understandable that if the total area S4 of the auxiliary holes 112 is too small, on the one hand, during the injection process, the injection time increases, which will lead to a decrease in the injection efficiency, and there will also be a risk of electrolyte overflow, which will cause the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the auxiliary holes 112, and the effect of improving battery safety is limited. On the contrary, if the total area S4 of the auxiliary holes 112 is too large, the auxiliary holes 112 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the welding area between the disk body 110 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance value of the battery. By setting the range of S4 / S1 to 9% to 21%, it is possible to ensure good welding effect between the disc body 110 and the winding core 200 while taking into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disc 100, and also effectively avoid increasing the internal resistance of the battery.

[0072] As mentioned above, the shape of the disk body 110 is a closed figure composed of multiple arc edges 114 and multiple concave edges 115 that are alternately connected end to end, so that the outer periphery of the disk body 110 includes multiple arc edges 114 that are disconnected from each other. As mentioned above, the two ends of each arc edge 114 can be extended to connect to each other to form a complete circle. Therefore, the disk body 110 can be regarded as a circular component. Therefore, it can be understood that these arc edges 114 themselves are partial arc segments of a complete circle, and multiple flanges 120 are arranged on these arc edges 114 one by one, and each flange 120 extends along the edge of the arc edge 114, so that each flange 120 is also in an arc shape. It should be noted that the arc length of the flange 120 can be less than the arc length of the arc edge 114. In this case, the notch 113 and the flange 120 are not directly connected.

[0073] In some embodiments, Fig. 9 As shown, the circumference of the plate body 110 is H1, the total arc length of the flange 120 is H2, and the range of H2 / H1 is 42% to 58%, that is, 42%≤H2 / H1≤58%. For example, the circumference H1 of the plate body 110 is 142mm, the total arc length H2 of the flange 120 is 70.68mm, and H2 / H1 is 49.77%. Among them, the circumference H1 of the plate body 110 refers to the circumference of the complete circular figure where the arc edge 114 is located, that is, Figure 5 The perimeter of the outer contour of the middle shaded area, and the total arc length of the flange 120 is H2, which refers to the sum of the arc lengths of the multiple flanges 120 ( Fig. 9Only the arc length of one section of the flange 120 is marked), for example, the disk body 110 is provided with a total of 4 sections of flanges 120, and the arc length of each section is 17.67 mm, then the total arc length H2 of the flange 120 is 70.68 mm.

[0074] It is understandable that when welding the flange 120 to the shell 300, since the clamping tooling will occupy part of the flange 120, if the total arc length H2 of the flange 120 is too small, it will be difficult to position, and it will also affect the actual welding area, so that the effective welding area is reduced, which will lead to a decrease in the current capacity of the welding point, and the problem of excessive temperature rise will occur in subsequent use, and the internal resistance will be increased, thereby affecting the battery performance. On the contrary, if the total arc length H2 of the flange 120 is too large, the weight of the negative electrode collector 100 will be increased, thereby reducing the energy density of the battery, and it will also cause the welding wire to be too long, and the excessively long welding wire will not only not reduce the resistance of the battery, but will reduce the reliability of the welding, for example, it will increase the risk of leakage, cold welding, and leaking welding at the welding point, which may increase the internal resistance of the battery. By setting the range of H2 / H1 to 42% to 58%, it is possible to ensure a good welding effect between the flange 120 and the shell 300 while ensuring that the negative electrode collector 100 is lighter, thereby improving the energy density of the battery and effectively avoiding an increase in the internal resistance of the battery.

[0075] In some embodiments, Fig. 9 As shown, the circumference of the plate body 110 is H1, the total arc length of the notch 113 is H3, and the range of H3 / H1 is 25% to 38%, that is, 25%≤H3 / H1≤38%. For example, the circumference of the plate body 110 is H1, which is 142 mm, and the total arc length of the notch 113 is H3, which is 45.32 mm, and H3 / H1 is 31.92%. Among them, the circumference of the plate body 110 is H1, which refers to the circumference of the complete circular figure where the arc edge 114 is located, that is, Figure 5 The circumference of the outer contour of the middle shaded area, and the total arc length H3 of the notch 113 refers to the arc length after the arc length of all arcs along the edge 114 is removed from the circumference of the disk body 110, that is, Fig. 9 The sum of the arc lengths of the dashed lines in ( Fig. 9 Only the arc length of a dotted line is marked in the figure), for example, the disk body 110 is provided with a total of 4 notches 113, and the arc length of each single notch 113 is 11.33 mm, then the total arc length H3 of the notch 113 is 45.32 mm.

[0076] It is understandable that if the total arc length H3 of the notch 113 is too short, on the one hand, during the injection process, the injection time increases, which will lead to a decrease in the injection efficiency, and there will also be a risk of electrolyte overflow, which will cause the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the notch 113, and the effect of improving the safety of the battery is limited. On the contrary, if the total arc length H3 of the notch 113 is too long, the notch 113 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the actual effective welding area between the disk body 110 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance value of the battery. By setting the range of H3 / H1 to 25% to 38%, it is possible to ensure good welding effect between the disc body 110 and the winding core 200 while taking into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disc 100, and also effectively avoid increasing the internal resistance of the battery.

[0077] In some embodiments, Fig. 9 As shown, the maximum depth H4 of the notch 113 is in the range of 2 to 5 mm, that is, 2 mm ≤ H4 ≤ 5 mm. It should be noted that the maximum depth H4 of the notch 113 refers to the distance between the highest point of the reference line of the outer periphery of the disk body 110 and the deepest point of the notch 113. For example, Fig. 9 The shape of the concave edge 115 shown in the figure is an arc, and its deepest point is at the midpoint of the arc-shaped concave edge 115, and the highest point of the reference line of the outer periphery of the disk body 110 is at the midpoint of the dotted line. Therefore, in this case, the maximum depth H4 is the distance between the midpoint of the concave edge 115 and the midpoint of the dotted line.

[0078] It is understandable that if the maximum depth H4 of the notch 113 is too small, that is, the depth of the notch 113 is too shallow, the area of ​​the notch 113 will be smaller, and the channel formed by the notch 113 and the shell 300 will be narrow. On the one hand, during the injection process, the notch 113 does not significantly improve the injection efficiency, and there is still a risk of electrolyte overflow, which may cause the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase manufacturing costs. On the other hand, when a short circuit or other thermal runaway occurs during use of the battery, the gas generated inside the battery cannot be discharged in time through the notch 113, and the effect on improving battery safety is limited. On the contrary, if the maximum depth H4 of the notch 113 is too large, that is, the depth of the notch 113 is too deep, the notch 113 will occupy the welding area on the disk surface of the disk body 110, resulting in a reduction in the actual effective welding area between the disk body 110 and the negative terminal 220, and the current capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety issues such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance of the battery. By setting the maximum depth H4 of the notch 113 in the range of 2 to 5 mm, it is possible to ensure a good welding effect between the disk body 110 and the winding core 200 while taking into account the injection efficiency and exhaust efficiency of the disk body 110, and it can also effectively avoid increasing the internal resistance of the battery.

[0079] like Fig. 9 As shown, in some embodiments, the central hole 111 and the arc edge 114 are arranged co-centrically, the radius of the disk body 110 is L1, the distance between the inner edge of the auxiliary hole 112 and the center of the central hole 111 is L2, and the range of L2 / L1 is 18% to 36%, that is, 18%≤L2 / L1≤36%. For example, L1 is 22.6 mm, L2 is 6 mm, and L2 / L1 is 26.55%.

[0080] It can be understood that the size of the cylindrical lithium-ion battery is basically fixed, that is, the shell diameter of the cylindrical lithium-ion battery is determined, so the diameter of the disk body 110 of the negative electrode current collector disk 100 assembled into the shell is basically determined, and because the center hole 111 is located at the center of the disk body 110, if L2 / L1 is too small, the auxiliary hole 112 and the center hole 111 are too close. In this way, the structural strength of the connecting part between the auxiliary hole 112 and the center hole 111 may be insufficient, and there is a risk of breaking. Moreover, once this part is broken, metal chips will be generated, and the burrs generated at the fracture are also easy to deform inward and pierce the diaphragm. Both metal chips and burrs may cause short circuit failure of the battery, posing a safety risk. On the contrary, if L2 / L1 is too large, the auxiliary hole 112 is too far from the center hole 111. In this way, when the electrolyte is injected through the center hole 111, when the center hole 111 cannot meet the injection speed requirement, the time for the electrolyte to spread through the disk surface of the disk body 110 to the auxiliary hole 112 will increase, and during the electrolyte spreading process, the electrolyte will continue to be injected into the battery, which is easy to cause overflow, thereby causing the shell to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase manufacturing costs. By setting the range of L2 / L1 to 18% to 36%, it is possible to take into account the structural strength of the connecting part between the center hole 111 and the auxiliary hole 112 while ensuring the auxiliary injection effect of the auxiliary hole 112.

[0081] The effects of the present application are further described below with specific examples and comparative examples.

[0082] It should be noted that the following embodiments and comparative examples of the present application are designed and manufactured based on the 4680 cylindrical lithium-ion battery commonly used in the art. Therefore, in addition to manufacturing the negative electrode collector 100 according to the aforementioned structure, other components and materials can be obtained by referring to the 4680 cylindrical lithium-ion battery. For example, the positive electrode sheet, the negative electrode sheet and the electrolyte can be obtained by referring to the following preparation method:

[0083] Preparation of positive electrode sheet: Take lithium nickel cobalt manganese oxide, carbon nanotube conductive agent, conductive carbon black, and polyvinylidene fluoride PVDF binder as solid substances of positive electrode slurry, disperse the solid substances in N-methyl-2-pyrrolidone, mix them evenly in a homogenizer, apply the slurry on both sides of aluminum foil, and dry to obtain a positive electrode sheet.

[0084] Preparation of negative electrode sheet: Take negative electrode active material, acetylene black conductive agent, thickener (hydroxymethyl cellulose), and polyacrylate binder as solid substances of negative electrode slurry, disperse the solid substances in deionized water, mix them evenly in a homogenizer, apply the slurry on both sides of copper foil, and dry to obtain negative electrode sheet.

[0085] Preparation of electrolyte: Ethylene carbonate, ethyl methyl carbonate and diethyl carbonate are mixed to obtain an organic solvent, and then fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte.

[0086] The components and materials obtained in the above manner can be assembled according to the known technology in the art to obtain an experimental cylindrical lithium-ion battery. For example, after the positive electrode sheet and the negative electrode sheet are rolled, slit, and die-cut, they are wound together with the diaphragm, and the positive electrode sheet, the negative electrode sheet, and the diaphragm are wound by a winding machine to form a winding core 200, and the positive electrode tabs and negative electrode tabs are cut and stacked at both ends of the winding core 200, and then the negative electrode collector plate 100 and the positive electrode collector plate are welded to the winding core 200, and then the negative electrode collector plate 100 is welded to the shell 300, and the negative electrode cover plate 500 is welded to the shell 300, and the injection, sealing, and formation processes are completed to obtain an experimental cylindrical lithium-ion battery.

[0087] Embodiment 1:

[0088] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector disc 100, and the negative electrode current collector disc 100 includes a disc body 110 and four flanges 120 protruding from the outer periphery of the disc body 110. One side of the disc body 110 of the negative electrode current collector disc 100 is laser welded to the winding core 200, and the flange 120 is in contact with the shell wall of the shell 300 in the direction away from the winding core 200, and the two are connected by laser through-welding. The disc body 110 is provided with a center hole 111 located at its center and four auxiliary holes 112 located on the periphery of the center hole 111. Four arc-shaped notches 113 are also provided on the outer periphery of the disc body 110. The midpoints of the edges 114 of each arc, the center of the auxiliary hole 112 and the center of the center hole 111 are collinear, and the negative electrode current collector disc 100 also meets the following parameters:

[0089] The area S1 of the disk body 110 is 1604.6 mm 2 The total area S2 of the notch 113 is 95.56mm 2 ; The area S3 of the center hole 111 is 28.27mm 2 The total area S4 of the auxiliary hole 112 is 226.27mm 2 ; The circumference of the disk body 110 is H1, which is 142 mm; the total arc length H2 of the flange 120 is 70.68 mm; the total arc length H3 of the notch 113 is 45.32 mm; the depth H4 of the notch 113 is 3 mm; the radius L1 of the arc edge 114 (disk body 110) is 22.6 mm; the distance L2 from the innermost side of the auxiliary hole 112 to the center position of the center hole 111 is 6 mm.

[0090] From the above, it can be seen that in the negative electrode current collecting disk 100, S2 / S1=6%, S3 / S1=2%, S4 / S1=14%, H2 / H1=50%, H3 / H1=32%, and L2 / L1=27%.

[0091] Embodiment 2:

[0092] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: S2 / S1=4%, S4 / S1=16%, H2 / H1=54%, H3 / H1=29%, H4=2mm, L2 / L1=24%.

[0093] Embodiment 3:

[0094] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: S2 / S1=8%, S4 / S1=12%, H2 / H1=46%, H3 / H1=33%, H4=4mm, L2 / L1=30%.

[0095] Comparative Example 1:

[0096] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which is different from Example 1 in that: S2 / S1=1%, H3 / H1=14.8%, and H4=0.9 mm.

[0097] Comparative Example 2:

[0098] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: S2 / S1=15%, H3 / H1=41%, and H4=5.83 mm.

[0099] Comparative Example 3:

[0100] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between Comparative Example 3 and Example 1 is that S4 / S1=5%.

[0101] Comparative Example 4:

[0102] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 4 and the embodiment 1 is that: S4 / S1=25%.

[0103] Comparative Example 5:

[0104] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 100, which is different from Example 1 in that: S3 / S1=0.5%

[0105] Comparative Example 6:

[0106] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: S3 / S1=8%

[0107] Comparative Example 7:

[0108] Comparative Example 7 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 7 and the embodiment 1 is that L2 / L1 = 12%.

[0109] Comparative Example 8:

[0110] Comparative Example 8 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 8 and the embodiment 1 is that L2 / L1 = 46%.

[0111] Comparative Example 9:

[0112] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 9 and the embodiment 1 is that H2 / H1=35%.

[0113] Comparative Example 10:

[0114] Comparative Example 10 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that: H2 / H1=68%.

[0115] Comparative Example 11:

[0116] Comparative Example 11 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that S2 / S1=4.1%, H3 / H1=20%.

[0117] Comparative Example 12:

[0118] Comparative Example 12 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that S2 / S1=8.3%, H3 / H1=45%.

[0119] Comparative Example 13:

[0120] Comparative Example 13 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that S2 / S1=2.6%, H4=1.25mm.

[0121] Comparative Example 14:

[0122] Comparative Example 14 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that S2 / S1=14.8%, H4=6.5 mm.

[0123] Table 1 below evaluates the structural strength, liquid injection rate, welding temperature rise and welding internal resistance of the negative electrode current collector 100 manufactured in the above-mentioned embodiment and comparative example.

[0124] The specific test method for the structural strength is as follows: take the negative electrode current collector disc 100, cut the connection between the disc body 110 and the flange 120 with scissors, remove the flange 120, fold and unfold along the connecting line between the auxiliary hole 112 and the center hole 111 of the disc body 110 once, repeat several times until the connection between the notch 113 and the center hole 111 is completely broken, and stop, and record the number of foldings. In each side folding, the two half surfaces need to be completely fitted together, and then opened to 180° after folding.

[0125] The specific test method for the injection rate is as follows: the negative electrode current collecting plate 100 manufactured in the above-mentioned embodiment and the comparative example is installed into the battery, and the normal battery cell manufacturing process is carried out to the groove rolling process and then to the injection stage, 75g of electrolyte is injected into the liquid holding cup, and the liquid holding cup is pressed into the groove of the groove rolling process, and the sealing ring below the liquid holding cup is completely close to the deep end surface of the groove, and then the liquid is injected. First, the negative pressure in the liquid holding cup is pumped to -90Kpa, and it can be observed from the liquid holding cup that the electrolyte height decreases, and the electrolyte flows into the battery. After maintaining for 40s, it is switched to positive pressure injection, and nitrogen is filled into the battery so that the inside of the battery gradually becomes a positive pressure of 0.8Mpa. The electrolyte in the liquid holding cup continues to flow into the battery, and the height of the electrolyte in the liquid holding cup gradually decreases, and then it is adjusted to negative pressure injection, and the positive pressure injection and negative pressure injection are repeatedly cycled until the electrolyte in the liquid holding cup completely flows into the battery, and the time taken for the electrolyte height in the liquid holding cup to drop to 0 is recorded.

[0126] The specific test method for welding temperature rise is as follows: the negative electrode current collecting disc 100 manufactured in the above-mentioned embodiment and comparative example is assembled into an experimental cylindrical lithium-ion battery, a through hole with a diameter of 3 mm is drilled on the negative electrode cover plate 500 of the experimental cylindrical lithium-ion battery, a temperature control line is passed through the through hole, and affixed to the weld mark of the negative electrode current collecting disc 100 and the negative end 220 of the winding core 200, and the negative electrode cover plate 500 is sealed after liquid injection according to the normal sample preparation process, and the battery is divided into different capacities to make a qualified cylindrical lithium-ion battery, and 10 cycles of charge and discharge are performed at a high rate of 3C. After 10 cycles of charge and discharge, the temperature data of the welding area collected by the temperature control line is obtained, and the maximum value Tmax within the temperature fluctuation range within 10 cycles is taken and recorded.

[0127] The specific test method for welding internal resistance is as follows: the negative electrode current collecting disc 100 and the winding core 200 manufactured in the above-mentioned embodiments and comparative examples are welded and then placed in the shell 300, and welding is performed according to the normal process. The batteries all adopt a ternary high-nickel system, and the ratio, electrolyte, positive and negative electrode formula, and material selection are all kept consistent. The flange 120 of the negative electrode current collecting disc 100 is penetrated and welded with the shell wall of the shell 300. The welding parameters are: welding focal length 0, welding speed 160mm / s, welding power 330W, and a weld mark with a width of 0.6mm is welded along the arc length of the flange 120, and then the subsequent liquid filling and sealing are carried out, and the capacity is divided. After the qualified cylindrical lithium-ion battery is made, its internal resistance is tested offline.

[0128] Table 1

[0129]

[0130]

[0131] As shown in Table 1, the range of S2 / S1 is set at 2% to 10%, the range of S3 / S1 is set at 1% to 3%, the range of S4 / S1 is set at 9% to 21%, the range of H2 / H1 is set at 42% to 58%, the range of H3 / H1 is set at 25% to 38%, the range of H4 is set at 2 to 5 mm, the range of L2 / L1 is set at 18% to 36%, the injection time is usually 705 to 708 seconds, the number of folding times is usually 11 times, and the maximum temperature rise at the welding position is 117° to 118°, and the internal resistance of the battery is 2.7mΩ. It can be seen that within the above numerical range, the structural strength, injection rate, welding temperature rise and welding internal resistance of the negative electrode collector can be well balanced, thereby effectively improving the safety and charge and discharge performance of the battery, and reducing the production cost of the battery.

[0132] As can be seen from Table 1, if S2 / S1 is too large (increasing the depth of the notch 113 and increasing the arc length of the notch 113), although the injection rate can be increased, the temperature rise at the welding position between the disc body 110 and the winding core 200 will increase significantly, and the internal resistance of the battery will increase; on the contrary, if S2 / S1 is too small, the injection rate will decrease. Therefore, setting S2 / S1 within a reasonable range can balance the injection rate, welding temperature rise and internal resistance of the negative electrode current collector disc 100.

[0133] As can be seen from Table 1, if S3 / S1 is too large, although the injection rate can be increased, the structural strength of the negative electrode current collector 100 will be reduced to a certain extent, the temperature rise of the welding position between the disc body 110 and the winding core 200 will also increase, and the internal resistance of the battery will increase; on the contrary, if S3 / S1 is too small, although the structural strength of the negative electrode current collector 100 can be improved and the internal resistance of the battery and the welding temperature rise can be ensured to be within a reasonable range, the injection rate will be reduced. Therefore, setting S3 / S1 within a reasonable range can balance the structural strength, injection rate, welding temperature rise and internal resistance of the negative electrode current collector 100.

[0134] As can be seen from Table 1, if S4 / S1 is too large, although the injection rate can be increased, the structural strength of the negative electrode current collector 100 will be significantly reduced, the temperature rise of the welding position between the disc body 110 and the winding core 200 will also increase, and the internal resistance of the battery will increase; on the contrary, if S4 / S1 is too small, although the structural strength of the negative electrode current collector 100 can be improved and the internal resistance of the battery and the welding temperature rise can be kept within a reasonable range, the injection rate will be reduced. Therefore, setting S4 / S1 within a reasonable range can balance the structural strength, injection rate, welding temperature rise and internal resistance of the negative electrode current collector 100.

[0135] As can be seen from Table 1, if H2 / H1 is too large or too small, the internal resistance of the battery and the temperature rise of the welding position between the disc body 110 and the winding core 200 will increase to a certain extent. Therefore, setting H2 / H1 within a reasonable range can balance the welding temperature rise of the negative electrode current collector disc 100 and the internal resistance of the battery.

[0136] It can be seen from Table 1 that, when the maximum depth H4 of the notch 113 remains unchanged, if H3 / H1 is too large, the opening area of ​​the notch 113 will become larger. In this way, although the injection rate can be increased, the temperature rise of the welding position between the disc body 110 and the winding core 200 will increase to a certain extent, and the internal resistance of the battery will increase; on the contrary, if H3 / H1 is too small, the opening area of ​​the notch 113 will become smaller. In this way, although the temperature rise of the welding position between the disc body 110 and the winding core 200 and the internal resistance of the battery can be ensured to be within a reasonable range, the injection rate will be reduced to a certain extent.

[0137] It can be seen from Table 1 that, when the arc length of the notch 113 remains unchanged, if H4 is too large, the opening area of ​​the notch 113 will become larger. In this way, although the injection rate can be increased, the temperature rise of the welding position between the disc body 110 and the winding core 200 will increase to a certain extent, and the internal resistance of the battery will increase; on the contrary, if H4 is too small, the opening area of ​​the notch 113 will become smaller. In this way, although the temperature rise of the welding position between the disc body 110 and the winding core 200 and the internal resistance of the battery can be ensured to be within a reasonable range, the injection rate will be reduced to a certain extent.

[0138] As can be seen from Table 1, if L2 / L1 is too large or too small, the structural strength of the negative electrode current collector 100 will be significantly reduced, and if L2 / L1 is too large, the injection time will be increased to a certain extent, thereby affecting the injection rate. Therefore, setting L2 / L1 within a reasonable range can ensure that the structural strength of the negative electrode current collector 100 meets the requirements while balancing the injection rate.

[0139] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present implementation. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0140] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A negative electrode current collector for a cylindrical lithium-ion battery, characterized in that: The invention comprises a disk body (110) and a flange (120) protruding along one side of the outer periphery of the disk body (110); the disk body (110) is shaped as a closed figure composed of a plurality of circular arc edges (114) and a plurality of concave edges (115) connected alternately end to end, the flange (120) is arranged on the circular arc edges (114), the concave edges (115) define a notch (113) at the outer periphery of the disk body (110), and the disk body (110) is provided with a central portion thereof. The disk body (110) comprises a central hole (111) and at least one auxiliary hole (112) located on the periphery of the central hole (111), the area of ​​the disk body (110) is S1, the total area of ​​the notch (113) formed by taking the peripheral edge line of the disk body (110) as a reference is S2, and the range of S2 / S1 is 2% to 10%, wherein the area of ​​the disk body (110) is the area of ​​the disk body (110) when the central hole (111), the auxiliary hole (112) and the notch (113) are not provided.

2. The negative electrode current collector according to claim 1, characterized in that: The area of ​​the central hole (111) is S3, and the range of S3 / S1 is 1% to 3%.

3. The negative electrode current collector according to claim 1, characterized in that: The total area of ​​the auxiliary holes (112) is S4, and the range of S4 / S1 is 9% to 21%.

4. The negative electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The circumference of the disk body (110) is H1, the total arc length of the flange (120) is H2, and the range of H2 / H1 is 42% to 58%.

5. The negative electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The circumference of the disk body (110) is H1, the total arc length of the notch (113) is H3, and the range of H3 / H1 is 25% to 38%.

6. The negative electrode current collecting disk according to claim 5, characterized in that: The shape of the concave edge (115) is arc-shaped, and the maximum depth of the notch (113) is H4, and the range of H4 is 2 to 5 mm.

7. The negative electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The radius of the disk body (110) is L1, the distance between the inner edge of the auxiliary hole (112) and the center of the central hole (111) is L2, and the range of L2 / L1 is 18% to 36%.

8. The negative electrode current collecting disk according to claim 7, characterized in that: The auxiliary hole (112) is a waist-shaped hole, and the long axis direction of the auxiliary hole (112) is consistent with the radius direction of the disk body (110).

9. The negative electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The number of the circular arc edges (114), the concave edges (115) and the auxiliary holes (112) is four, the four circular arc edges (114) and the four auxiliary holes (112) are arranged in one-to-one correspondence, and the midpoints of the correspondingly arranged circular arc edges (114), the centers of the auxiliary holes (112) and the center of the center hole (111) are collinear.

10. A cylindrical lithium-ion battery, characterized in that: It comprises a shell (300), a winding core (200) and a negative electrode current collecting disc (100) according to any one of claims 1 to 9, wherein the disc body (110) of the negative electrode current collecting disc (100) is connected to the negative end (220) of the winding core (200), and the flange (120) of the negative electrode current collecting disc (100) is connected to the shell wall of the shell (330) by laser penetration welding.

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